The evidence is clear: better teachers improve student outcomes, ranging from test scores to college attendance rates to career earnings. Federal policy has begun to catch up with these findings in its recent shift from an effort to ensure that all teachers have traditional credentials to policies intended to incentivize states to evaluate and retain teachers based on their classroom performance. But new federal policy can be slow to produce significant change on the ground. The Obama Administration has pushed the creation of a new generation of meaningful teacher evaluation systems at the state level through more than $4 billion in Race to the Top funding to 19 states and No Child Left Behind (NCLB) accountability waivers to 43 states. A majority of states have passed laws requiring the adoption of teacher evaluation systems that incorporate student achievement data, but only a handful had fully implemented new teacher evaluation systems as of the 2012-13 school year. As the majority of states continue to design and implement new evaluation systems, the time is right to ask how existing teacher evaluation systems are performing and in what practical ways they might be improved. This report helps to answer those questions by examining the actual design and performance of new teacher evaluation systems in four urban school districts that are at the forefront of the effort to meaningfully evaluate teachers. Overall, the authors' analysis leaves them optimistic that new evaluation systems meaningfully assess teacher performance. Despite substantial differences in how individual districts designed their systems, each is performing within a range of reliability and validity that is both consistent with respect to prior research and useful with respect to improving the prediction of teacher performance. With modest modifications, these systems, as well as those yet to be implemented, will better meet their goal of assuring students' access to high-quality teachers.